Conventional steam boilers have a number of economic shortcomings and cause many operating problems in combined cycle applications, particularly those of small capacity using gas turbines in the 4000-25000 Kw range. Among the major contributors to these drawbacks are the complex systems utilized to control the operation of combined cycle power plant boilers (typical prior art control systems for combined cycle power plants are disclosed in U.S. Pat. Nos. 3,505,811 to Underwood and 2,965,765 to Martz et al).
The complex prior art boiler control systems tend to have large numbers of components that are subject to malfunction which makes maintenance costs high and reduces boiler availability. Also, attended operation may be required for safe and efficient boiler operation.